Suspicious Windows AppX Deployment Unsigned Package Deployment (via appxdeployment-server)

title: Suspicious Windows AppX Deployment Unsigned Package Deployment (via appxdeployment-server)
id: d8ec15eb-0777-554c-99b5-4ade5ef93f2b
status: stable
description: This rule detects attempts to install unsigned MSIX/AppX packages using the -AllowUnsigned parameter via AppXDeployment-Server events
references:
    - https://attack.mitre.org/techniques/T1553/005/
    - https://attack.mitre.org/techniques/T1204/002/
    - https://docs.microsoft.com/en-us/powershell/module/appx/add-appxpackage
    - https://www.splunk.com/en_us/blog/security/msix-weaponization-threat-detection-splunk.html
author: Huntrule Team
date: 2026-01-14
tags:
    - attack.execution
    - attack.defense-impairment
    - attack.t1204.002
    - attack.t1553.005
logsource:
    product: windows
    service: appxdeployment-server
detection:
    selection:
        EventID: 603
        Flags: '8388608'
    condition: selection
falsepositives:
    - Unknown
level: medium